1. Field of the Invention
The present invention relates to organopolysiloxane compositions of shiny and gel-like appearance, which contain no gelling agent. The present compositions constitute an excipient of choice for incorporating substances that are incompatible with the gelling agents conventionally used in preparations of gel-like appearance. The present compositions may serve as a base for the manufacture of creams used in many fields, in particular in cosmetology, dermatology, pharmaceutics and the like. The present invention very especially relates to care or makeup creams for the skin, the face and the body in general including the nails, the scalp and the eyelashes.
2. Discussion of the Background
Many products already exist both as cosmetic and dermatological or pharmaceutical products which are oil-in-water (O/W) emulsions. Depending on the choice of the starting materials (emulsifying agents, fatty substances, polyol polymers and other hydrophilic starting materials and the like), these dispersions may be provided in the form of creams of varied textures: more or less thick, more or less shiny and more or less gel-like.
In order to obtain a cream which is pleasant from a sensory (its "feel") and from a visual (its appearance) point of view, the search is more for a shiny and gel-like appearance rather than a runny and matt appearance. In order to obtain such creams, a gelling agent (also known as a thickener) is customarily used, which is incorporated into the continuous aqueous phase of the emulsion and which imparts its consistency to the cream. The majority of the gelling agents conventionally used are carboxyvinyl polymers of the Carbomers (CTFA) type, which are neutralized by a base (sodium hydroxide or triethanolamine).
It happens, however, that certain starting materials, which are moveover indispensable in the composition of these creams, do not permit the use of the above-mentioned gelling agents as a result of incompatibility. It is known, for example, that electrolytes (inorganic and organic salts) are incompatible with neutralized carboxyvinyl polymers because of the fact that they "break" the emulsion or even liquefy it.
A large number of starting materials used in O/W emulsions of gel-like appearance are either electrolytes in their entirety or mixtures of various compounds which may include non-negligible amounts of electrolytes. Thus, formulations containing carboxyvinyl polymers and electrolytes lack consistency, and their appearance renders them inappropriate for use in the above-mentioned fields. This same problem is also encountered with any compound, other than an electrolyte, displaying an incompatibility with these carboxyvinyl gelling agents.
One solution consists of using, in place of the carboxyvinyl polymer gelling agents, gelling agents of the polysaccharide type such as natural gum of cellulose, guar, or xanthan. However, in order to obtain a consistency equivalent to that provided by the gelling agents of carboxyvinyl polymer type, large amounts of such gelling agents must be incorporated in order to increase the viscosity of the emulsion. This is a nuisance in the above-mentioned applications, because the cream of gel-like appearance then becomes very sticky when applied to the skin, the hair, etc.
It is moreover known, according to U.S. Pat. No. 5,013,715, to produce an anhydrous base of pasty and matt appearance in order to prepare cosmetic creams. This base consists of a fluid organopolysiloxane oil of the methylphenylpolysiloxane type, used alone or mixed with a cyclic polydimethylsiloxane (PDMS) and/or a linear PDMS, and of sucrose ester. This ester has a pronounced lipophilic nature, because its hydroxyl number is less than 200, in order to be compatible with the fluid organopolysiloxane. The addition of water to this anhydrous paste leads to the production of a composition which is applied to the skin with difficulty.
It is also known, according to EP-A-158,108, that it is possible to produce O/W emulsions by adding water to anhydrous detergent compositions comprising an oily phase, a detergent emulsifying agent and a sucrose ester. These emulsions are milky creams of low viscosity, which are difficult to apply to the skin and the hair.
The need thus remains for gel-like compositions that do not display the disadvantages encountered with the known preparations, in particular of runny consistency, of instability, of matt appearance, of unpleasant sensation to the touch, of sticky effect, of unsatisfactory spreading and of incompatibility with certain compounds.